Stellar Cartography

A Candidate High-Velocity Exoplanet System In The Galactic Bulge

By Keith Cowing

Status Report

astro-ph.EP

October 16, 2024

Filed under adaptive optics, astro-ph.EP, astronomy, Exomoon, exoplanet, Gaia DR3, galactic bulge, gas giant, imaging, Keck-I, microlensing, MOA-2011-BLG-262, Nancy Grace Roman Galactic Exoplanet Survey, Stellar Cartography, telescope

A Candidate High-Velocity Exoplanet System In The Galactic Bulge — Left: A zoom-in on the stacked Kp-band image of MOA-2011-BLG-262, with the brighter source star near center and the faint lens star candidate indicated with the cross-hair. Middle: Zoomed-in frame with a single-PSF model fit to the source star and subtracted from the frame, the remaining flux comes primarily from the lens and is indicated with the cross-hair. The other bright nearby stars are also subtracted with the same PSF model. Right: Zoomed-in frame with the PSF model fit and subtracted from the source and lens stars. North is up, East is left in all frames. Note there are several faint ambient field stars that are at or below the default detection threshold in DAOPHOT. — astro-ph.EP

We present an analysis of adaptive optics (AO) images from the Keck-I telescope of the microlensing event MOA-2011-BLG-262. The original discovery paper by Bennett et al. 2014 reports two distinct possibilities for the lens system; a nearby gas giant lens with an exomoon companion or a very low mass star with a planetary companion in the galactic bulge.

The ∼10 year baseline between the microlensing event and the Keck follow-up observations allows us to detect the faint candidate lens host (star) at K=22.3 mag and confirm the distant lens system interpretation.

The combination of the host star brightness and light curve parameters yields host star and planet masses of M_host=0.19±0.03M_⊙ and m_p=28.92±4.75M_⊕ at a distance of DL=7.49±0.91kpc.

We perform a multi-epoch cross reference to Gaia DR3 and measure a transverse velocity for the candidate lens system of vL=541.31±65.75 km s⁻¹. We conclude this event consists of the highest velocity exoplanet system detected to date, and also the lowest mass microlensing host star with a confirmed mass measurement.

The high-velocity nature of the lens system can be definitively confirmed with an additional epoch of high-resolution imaging at any time now. The methods outlined in this work demonstrate that the Roman Galactic Exoplanet Survey (RGES) will be able to securely measure low-mass host stars in the bulge.

Sean K. Terry, Jean-Philippe Beaulieu, David P. Bennett, Aparna Bhattacharya, Jon Hulberg, Macy J. Huston, Naoki Koshimoto, Joshua W. Blackman, Ian A. Bond, Andrew A. Cole, Jessica R. Lu, Clément Ranc, Natalia E. Rektsini, Aikaterini Vandorou

Comments: 21 pages, 6 figures, 4 tables, submitted to AJ
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Astrophysics of Galaxies (astro-ph.GA); Solar and Stellar Astrophysics (astro-ph.SR)
Cite as: arXiv:2410.09147 [astro-ph.EP] (or arXiv:2410.09147v1 [astro-ph.EP] for this version)
https://doi.org/10.48550/arXiv.2410.09147
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Submission history
From: Sean Terry
[v1] Fri, 11 Oct 2024 18:00:01 UTC (10,812 KB)
https://arxiv.org/abs/2410.09147

Astrobiology,

Keith Cowing

Explorers Club Fellow, ex-NASA Space Station Payload manager/space biologist, Away Teams, Journalist, Lapsed climber, Synaesthete, Na’Vi-Jedi-Freman-Buddhist-mix, ASL, Devon Island and Everest Base Camp veteran, (he/him) 🖖🏻

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